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Rhamnus(plant)

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"Buckthorn" redirects here. For other plants of that name, seeList of plants known as buckthorn.

Rhamnus
Rhamnus cathartica
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Rhamnaceae
Tribe: Rhamneae
Genus: Rhamnus
L.
Species

See text

Rhamnus pumila,dwarf buckthorn

Rhamnusis agenusof about 140 acceptedspeciesofshrubsor smalltrees,commonly known asbuckthorns,in the familyRhamnaceae.Its species range from 1 to 10 m (3 to 33 ft) tall (rarely to 15 m, 50 ft) and are native mainly in east Asia and North America, but found throughout the temperate and subtropicalNorthern Hemisphere,and also more locally in the subtropicalSouthern Hemispherein parts ofAfricaandSouth America.One species, the common buckthorn (Rhamnus cathartica), is able to flourish as an invasive plant in parts of Canada and the U.S., where it has becomenaturalized.[1]

Bothdeciduousandevergreenspecies occur. The leaves are simple, 3 to 15 cm (1 to 6 in) long, and arranged alternately, in opposite pairs, or almost paired (subopposite). One distinctive character of many buckthorns is the way the veination curves upward towards the tip of the leaf. The plant bears fruits which are black or red berry-likedrupes.The name is due to the woody spine on the end of each twig in many species. One species is known to have potential to be used medicinally.[2]

Description[edit]

Rhamnusspecies are shrubs or small to medium-sized trees,[3]with deciduous or rarely evergreen foliage. Branches are unarmed or end in a woody spine. The leaf blades are undivided and pinnately veined. Leaf margins are serrate or rarely entire.Rhamnusspecies are generallydioecious,with male and female flowers on separate plants.[4]Most species have yellowish green, small, unisexual or rarely polygamous flowers; which are produced singly or in axillarycymes,cymoseracemes,or cymosepaniclescontaining a few flowers.Calyx tubecampanulate to cup-shaped, with 4 or 5 ovate-triangular sepals, which are adaxially ± distinctly keeled. Petals 4 or 5 but a few species may lack petals. The petals are shorter than the sepals. Flowers have 4 or 5 stamens which are surrounded by and equal in length the petals or are shorter. The anthers are dorsifixed. The superior ovary is free, rounded, with 2-4 chambers. Fruits are a 2-4 stoned, berrylike drupe, which is obovoid-globose or globose shaped. Seeds are obovoid or oblong-obovoid shaped, unfurrowed or abaxially or laterally margined with a long, narrow, furrow. The seeds have fleshy endosperm.[5]

Species[edit]

As of February 2023,Plants of the World Onlineaccepted the following species:[6]

Distribution[edit]

Rhamnushas a nearlycosmopolitan distribution,[9]with about 140 species which are native from temperate to tropical regions, the majority of species are from east Asia and North America, with a few species in Europe and Africa.[5]

North American species includeRhamnus alnifolia,alder-leaf buckthorn, occurring across the continent, andRhamnus crocea,hollyleaf buckthorn, in the west. Though not native to this region,Rhamnus catharticacan be found in North America.[10]

Buckthorns may be confused withdogwoods,which share the curved leafvenation;indeed, "dogwood" is a local name forR. prinoidesin southern Africa. The two plants are easy to distinguish by slowly pulling a leaf apart; dogwoods will exude thin, white latex strings, while buckthorns will not.

Invasive species[edit]

Rhamnus cathartica,the common buckthorn, is considered aninvasive speciesin the United States[11]and by many local jurisdictions and state governments, including Minnesota[12]and Wisconsin.[13]

The common buckthorn is well-adapted to spreading in Canada and the U.S.[1]It is an efficient grower that does not need much sunlight and or fertile soil.[1]Its seeds are hardy, as well as being able to grow and spread easily in a variety of environmental conditions.[1]Also other animals prefer to leave buckthorns alone because their leaves are not appetizing and their fruits are toxic to some animals.[1]Overall they are known to have a negative effect on their surrounding environment.[1]For example, the European buckthorn is blamed for increased frog egg mortality from a chemical it releases.[14]Other species, such as theRhamnus alaternusalso make chemicals that prevent other animals from consuming them.[2]

Ecology[edit]

Some species areinvasiveoutside their natural ranges.R. catharticawasintroducedinto theUnited Statesas agardenshrub and has become an invasive species in many areas there. It is a primary host of thesoybean aphid(Aphis glycines), apestforsoybeanfarmers across the US. The aphids use the buckthorn as a host for the winter and then spread to nearby soybean fields in the spring.[15]Italian buckthorn (R. alaternus), an evergreen species from the Mediterranean region, has become a serious weed in some parts ofNew Zealand,[16]especially onHauraki Gulfislands.

Buckthorns are used as food plants by thelarvaeof many Lepidoptera species.

The American species are known to be hosts for theoatfungusPuccinia coronata.In a 1930 study, both kerosene and salt were employed for eradication ofR. lanceolataand both proved to be less expensive than felling these bushes.[17]

Uses[edit]

Rhamnus cathartica

The fruit of most species contain a yellow dye and the seeds are rich in protein. Oils from the seeds are used for making lubricating oil, printing ink, and soap.[5]Many species have been used to makedyes.R. utilisprovides china green, a dye used to give a bright green color to silk and wool.[18]Another species, Avignon buckthorn (R. saxatilis) provides the yellow dyePersian berry,made from the fruit.

Some species may causedemyelinating polyneuropathies.[19]

The purging buckthorn (R. cathartica) is a widespreadEuropeannative species used in the past as apurgative.It was in mid 17th-century England the only native purgative.[20]It was also known pre-LinnaeusasSpina Cervina.[21]The berries ofSpina Cervinaare black and contain a greenish juice, along with four seeds apiece; this serves to distinguish them from those of theblack alderanddogberry,which contain only one or two apiece. Its syrup is said to be churlish.[22]Its toxicity makes this a very riskyherbal medicine,and it is no longer in use.[23]

R. prinoidesis known asgeshoinEthiopia,where it is used to make ameadcalledtej.

The speciesRhamnus alaternusshows some promise for medicinal use as well.[2]

See also[edit]

  • Sea buckthornorHippophae,an unrelated genus of shrubs with a similar common name
  • Frangula,a genus formerly included inRhamnus

References[edit]

  1. ^abcdefKnight, Kathleen S.; Kurylo, Jessica S.; Endress, Anton G.; Stewart, J. Ryan; Reich, Peter B. (2007-12-01). "Ecology and ecosystem impacts of common buckthorn (Rhamnus cathartica): a review".Biological Invasions.9(8): 925–937.doi:10.1007/s10530-007-9091-3.hdl:11299/175602.ISSN1573-1464.S2CID10701363.
  2. ^abcZeouk, Ikrame; Bekhti, Khadija (2020-03-01). "A critical overview of the traditional, phytochemical and pharmacological aspects of Rhamnus alaternus: a Mediterranean shrub".Advances in Traditional Medicine.20(1): 1–11.doi:10.1007/s13596-019-00388-8.ISSN2662-4060.S2CID199453600.
  3. ^Archibold, William; Brooks, Darin; Delanoy, L. (1997)."An investigation of the invasive shrub European Buckthorn, Rhamnus cathartica L., near Saskatoon, Saskatchewan".Canadian Field-Naturalist.111– via ResearchGate.
  4. ^Holmgren, Kjell; Oxelman, Bengt (2004). "Generic Limits in Rhamnus L. S.l. (Rhamnaceae) Inferred from Nuclear and Chloroplast DNA Sequence Phylogenies".Taxon.53(2): 383–390.doi:10.2307/4135616.JSTOR4135616.
  5. ^abc"Rhamnus".Flora of China.Retrieved2013-05-07– via eFloras.org,Missouri Botanical Garden,St. Louis, MO &Harvard University Herbaria,Cambridge, MA.
  6. ^"RhamnusL. "Plants of the World Online.Royal Botanic Gardens, Kew.Retrieved2023-02-11.
  7. ^"Common Buckthorn".Ontario's Invading Species Awareness Program.Retrieved27 May2019.
  8. ^"Rhamnus croceasubsp.ilicifolia(Kellogg) C.B.Wolf ".Plants of the World Online.Royal Botanic Gardens, Kew.Retrieved2024-03-09.
  9. ^"Rhamnus".Flora of Pakistan.Retrieved2013-05-07– via eFloras.org,Missouri Botanical Garden,St. Louis, MO &Harvard University Herbaria,Cambridge, MA.
  10. ^Kurylo, J. S.; Knight, K. S.; Stewart, J. R.; Endress, A. G. (2007). "Rhamnus cathartica: Native and naturalized distribution and habitat preferences1".The Journal of the Torrey Botanical Society.134(3): 420–430.doi:10.3159/1095-5674(2007)134[420:RCNAND]2.0.CO;2.ISSN1095-5674.S2CID86023237.
  11. ^"Common Buckthorn".National Invasive Species Information Center.Retrieved9 July2018.
  12. ^"Buckthorn".Minnesota Department of Natural Resources.Retrieved27 May2019.
  13. ^"Bucking a Thorny Invader"(PDF).Wisconsin Department of Natural Resources.Retrieved27 May2019.
  14. ^"Midwestern frogs decline, mammal populations altered by invasive plant, studies reveal".ScienceDaily.Retrieved2020-04-20.
  15. ^"SDSU Department of Plant Science: Managing Soybean Aphids".Sdstate.edu. 2012-04-03. Box: 2207A.Retrieved2013-05-07.
  16. ^"Rhamnus alaternus".Global Invasive Species Database(GISD).Retrieved2013-05-07.
  17. ^Dietz, S.M.; Leach, L.D. (1930).Methods of Eradicating Buckthorn (rhamnus) Susceptible to Crown Rust (puccinia Coronata) of Oats.USDA Circulars. Vol. 133. U.S. Department of Agriculture.
  18. ^Brunello, F. (1973).The Art of Dyeing in the History of Mankind.AATCC. p. 381.
  19. ^"Peripheral Neuropathy: Peripheral Nervous System and Motor Unit Disorders: Merck Manual Professional".Merckmanuals.Retrieved2013-05-07.
  20. ^Phil. trans.:Number 23, beginning the third year, March 11, 1666 at p.409, p.424
  21. ^Elizabeth Blackwell,"A Curious Herbal, Containing Five Hundred Cuts Of The Most Useful Plants"Archived2021-08-28 at theWayback Machine,p.134
  22. ^William Lewis,"An Experimental History Of The Materia Medica"
  23. ^Plants for a Future:Rhamnus cathartica

External links[edit]

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